This B/START application proposes to test hypothesis about the optokinetic and smooth pursuit eye movement systems in schizophrenic patients. Background: Despite decades of research on abnormal smooth pursuit eye movements in schizophrenia, the potential of this area of study remains unfulfilled. Current theory suggests that the abnormal pursuit is caused by dysfunction of cerebral, not brainstem, ocular motor regions. However, this theory remains unproven. An important test of it would be to examine an oculomotor system which shares brainstem regions with the pursuit system, but which bypasses cerebral regions. This system should function normally in schizophrenia. One such system is the optokinetic system, which is used to stabilize a steadily moving environment on the fovea. Only rarely has this system been studied in schizophrenia. The most recent study concluded that the optokinetic system of functions normally in schizophrenia (Latham et al., 1981), and this may be the predominant view in the field (Holzman, 1987). However, by today's standards, all of the previous studies of the optokinetic system in schizophrenia were much too limited in their methodology to support this conclusion. Therefore, the important hypothesis that the optokinetic system functions normally in schizophrenia remains to be adequately tested. Specific aims: To test the hypothesis that schizophrenic patients will have an abnormal pattern of responses to pursuit and optokinetic stimuli, indicating normal function of the optokinetic system and abnormal functions of the pursuit system. Preliminary studies : We have shown that patient shave abnormalities in the initiation and maintenance of smooth pursuit eye movements. Optokinetic testing will complement such ongoing studies in our laboratory. Methods: Pursuit and optokinetic eye movements will be tested in 20 normal controls, 20 schizophrenic patient with eye tracking disorder (ETD) and 20 non-ETD patient. The optokinetic stimulus will be a full-field, rotating environment, which will invoke optokinetic nystagmus (OKN). Measures of the slow phase in response to both pursuit and optokinetic stimuli will include initial acceleration and steady- state gain. In addition, the optokinetic stimulus will completely darkened during certain periods of time in order to test buildup and discharge of velocity storage, which is related to optokinetic after- nystagmus (OKAN). In addition, monocular testing in response to the optokinetic stimulus will test temporal-nasal preference, a characteristic of the optokinetic system.